The first use of the Dialing program，the upper left corner is always shown in the initialization，why?

Every time the first use of the phone program, the upper left corner is always shown in the initialization, when the number key and the number button can not be pressed, and locked for a long time.we know that Apple phones don't have this situation. Why do Ubuntu phones do this? Is it because of the efficiency of QML or others?
My device is Meizu pro5, you know, this performance is not bad. QML is too slow.
Finally, I would like to thank the developers for their continuous updates.

If the dial program is always running in the background, there is no such problem.
The problem arises when we exit the dial program and re run the dial program.
The signal of the telecom operator is very good!

I have a Meizu Pro5. I am on 15.04 on this device. I do not have the issue as reported by @sunshine_lamp. So in my case at least, this is not a reproduce-able issue on 15.04
I even rebooted my device to double check.

I can confirm this problem on my turbo vivid. I always had it. As a workaround I keep the dialer app open in background all the time. It bothers me that while it is "initializing" I cannot press the green button to redial the last dialed number. The green is kind of a light green and then, after a while, it turns normal green and I can use the app.